1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for completing wellbores for production of hydrocarbons from subsurface formations.
2. Background of the Art
Wellbores or wells are drilled in subsurface formations for the production of hydrocarbons (oil and gas) trapped in various zones at different depths. A completion assembly (sometimes referred to as the “lower completion assembly”) is placed inside the wellbore that includes packers that isolate production zones, sand screens to prevent flow of solid particles from the formation into the wellbore and flow devices, such as sleeve valves for treating the zones before production and production valve that allow the formation fluid to flow from their associated zones into wellbore. When the lower completion assembly is placed for the production of formation fluids, the production valves are closed so that the formation fluid does not flow to the inside of the lower completion assembly. Typically, there are several thousand feet of non-productive wellbore above the completion assembly. Before opening the production valves in the lower assembly, an isolation assembly is placed above the lower completion assembly. A packer is set in the annulus (space) between the isolation assembly and the lower completion to prevent flow of fluids though such annulus. The annulus, however, is filled with a fluid having a density that provides pressure inside the wellbore greater than the pressure in the formation along the entire depth of the wellbore to prevent blow outs. This fluid can flow from the inside of the lower completion assembly into the formation when the production valves are open. To place the isolation assembly, the production valves are opened before setting the packer, which causes the wellbore fluid to flow through the annulus around the unset packer into the formation, causing fluid loss and can also contain debris. This fluid flow is undesirable as it can hinder the setting of the packer and result in fluid loss from the wellbore into the production zones. It is therefore desirable to provide apparatus and methods to mitigate the effect of such fluid flow during the setting of the packer on the isolation assembly.
The disclosure herein provides apparatus and methods to restrict the flow of the fluid through an annulus between a completion assembly and the wellbore during isolating an annulus between the isolation assembly and the wellbore.